The use of aniline in oxime ligations or imine formation has been shown to be effective in increasing the overall reaction rate and to allow such reactions to occur at less acidic pH values (A. Dirksen, et al., “Nucleophilic Catalysis of Oxime Ligation Angew. Chem. Int. Ed. 2006, 45, 7581-7584 A. Dirksen, T. Hackeng and P. Dawson). However, such reactions have been limited to non-radiolabeled compounds.
As described in more detail below, it has now been surprisingly found that aniline can be used to radiostabilize the oxime ligation or imine formation reaction of radiolabeled reactants with the unexpected results of both improved reaction kinetics and significant radiostabilization.